Matthew 5:4

“Blessed are they that mourn, etc.] For sin, for their own sins; the sin of their nature, indwelling sin, which is always working in them, and is a continual grief of mind to them; the unbelief of their hearts, notwithstanding the many instances, declarations, promises, and discoveries of grace made unto them; their daily infirmities, and many sins of life, because they are committed against a God of love, grace, and mercy, grieve the Spirit, and dishonour the Gospel of Christ: who mourn also for the sins of others, for the sins of the world, the profaneness and wickedness that abound in it; and more especially for the sins of professors, by reason of which, the name of God, and ways of…”

“Blessed are they that mourn: for they shall be comforted--This "mourning" must not be taken loosely for that feeling which is wrung from men under pressure of the ills of life, nor yet strictly for sorrow on account of committed sins. Evidently it is that entire feeling which the sense of our spiritual poverty begets; and so the second beatitude is but the complement of the first. The one is the intellectual, the other the emotional aspect of the same thing. It is poverty of spirit that says, "I am undone"; and it is the mourning which this causes that makes it break forth in the form of a lamentation--"Woe is me! for I am undone." Hence this class are termed "mourners in Zion," or, as we…”

“Blessed are they that mourn - This is capable of two meanings: either, that those are blessed who are afflicted with the loss of friends or possessions, or that they who mourn over sin are blessed. As Christ came to preach repentance, to induce people to mourn over their sins and to forsake them, it is probable that he had the latter particularly in view. Compare 2 Corinthians 7:10. At the same time, it is true that the gospel only can give true comfort to those in affliction, Isaiah 61:1-3; Luke 4:18. Other sources of consolation do not reach the deep sorrows of the soul. They may blunt the sensibilities of the mind; they may produce a sullen and reluctant submission to what we cannot help:…”

“They that mourn - Either for their own sins, or for other men's, and are steadily and habitually serious. They shall be comforted - More solidly and deeply even in this world, and eternally in heaven. Matthew 5:5”

“5:4 Those who mourn were those who lamented the spiritual and national condition of Israel (see 23:37-39; Isa 61:2-3; Joel 1:8-13; 2:12-13, 18-19; Rom 9:1-5; 1 Cor 5:2; Jas 4:9). Personal grief, whether caused by sin or tragedy, may also be in view (Mark 16:10; Rev 18:11, 19). • will be comforted: The passive voice is used out of reverence for the holy name of God; the phrase could also be rendered God will comfort them (see also Matt 5:6-7, 9). Comfort will accompany the fulfillment of all that God has promised (Isa 40:1-2; 61:2-3).”

“Psa 6:1-9, Psa 13:1-5, Psa 30:7-11, Psa 32:3-7, Psa 40:1-3, Psa 69:29-30, Psa 116:3-7; Psa 126:5, Psa 126:6; Isa 12:1, Isa 25:8, Isa 30:19, Isa 35:10, Isa 38:14-19, Isa 51:11, Isa 51:12, Isa 57:18; Isa 61:2, Isa 61:3, Isa 66:10; Jer 31:9-12, Jer 31:16, Jer 31:17; Eze 7:16, Eze 9:4; Zac 12:10-14; Zac 13:1; Luk 6:21, Luk 6:25, Luk 7:38, Luk 7:50, Luk 16:25; Joh 16:20-22; Co2 1:4-7; Co2 7:9, Co2 7:10; Jam 1:12; Rev 7:14-17, Rev 21:4 Matthew 5:5”